The present invention relates to an antiplaque dentifrice containing a quaternary active ingredient and at least 1.5% and up to 2% betaine surfactant by weight, such as cocoamidopropylbetaine, lauramidopropylbetaine, cocobetaine, etc., which enhances foaming and does not inactivate the antibacterial activity of the quaternary compound. Nonionic surfactants fail to afford sufficient foaming, and anionic surfactants inactivate the quaternary antibacterial activity. Carbowax 600 (polyethylene glycol), and/or sorbitol replace propylene glycol and glycerin as humectant in order to afford stability to the betaine-containing composition. Also, carboxymethyl cellulose is preferably avoided because large organic molecules deactivate the quaternary compound. Nonionic gums such as hydroxyethylcellulose is used as gelling/thickening agent for the dental cream. Another essential ingredient of this dentifrice is a fluorine-containing compound capable of providing a fluoride ion. More specifically, this composition is free of anionic and nonionic surfactants, and contains only a minimal amount of glycerin, 1-10%, and preferably 5-7% by weight, as a fluoride stabilizer.
It has been found that the addition of a betaine surfactant to an antiplaque dental formulation based on quaternary active ingredients, improves the foaming characteristics thereof, without deactivating the quaternary antimicrobial activity. It has additionally been found that humectants such as polyethylene glycol and/or sorbitol are required in the betaine system to effect cosmetic stability, and that the gelling/thickening agent be limited to nonionic gums such as hydroxyethylcellulose.
In a copending patent application, filed of even date, is described a cosmetically stable antiplaque dentifrice based on polyethylene glycol and/or sorbitol completely replacing glycerin as the humectant. Accelerated aging studies have shown the fluoride stability in this dentifrice to be marginal but acceptable.
It has been found that incorporating small amounts of glycerin, up to a maximum of 10%, into the fluoride-containing formulation, markedly improves the long term fluoride stability in a polyethylene glycol humectant system alone, without adversely affecting the cosmetic stability of the dentifrice. Accordingly, the glycerine component herein functions as, and is used as a chemical stabilizer for the fluoride ingredient.
The ability of quaternary ammonium compounds to inhibit the formulation of dental plaque is well documented. These compounds, however, present a problem when formulated in a dentifrice in that they are deactivated by traditional anionic surfactants such as sodium lauryl sulfate. Stable, clinically effective dental formulations have been made with quaternary ammonium compounds and nonionic surfactants, but these formulations are very poor foamers and result in inferior products. Compositions containing antiplaque quaternary ammonium compounds and nonionic surfactants are disclosed in U.S. Pat. No. 4,080,441, No. 4,110,429, No. 4,118,472, No. 4,118,473, No. 4,118,475, No. 4,118,476, and British Pat. No. 1,573,356.
U.S. Pat. No. 4,161,518 discloses a dentifrice composition for inhibiting plaque formation containing 0.05-1% by weight of a quaternary ammonium organosiloxane as the active antibacterial agent in a suitable vehicle containing suitable polishing agents, fluoride compounds, anionic surfactants, flavoring and sweetening agents, thickening agents such as a carboxymethylcellulose, humectants such as glycerin, sorbitol and other polyhydric alcohols.
U.S. Pat. No. 3,988,435 discloses a pharmaceutical compositions including a dentifrice containing a quaternary ammonium dihydrochalcone glucoside as the antibacterial agent having a sweet taste, as well as abrasives, surfactants including nonionics and "derivatives of fatty amines with betaine structures," swelling, gelling or thickening agents such as hydroxyalkylcellulose particularly hydroxyethylcellulose, polyethylene glycols, polypropylene glycols, etc., humectants such as sorbitol, mannitol, glycerin, propylene glycol, colorants, and flavors.
All of aforesaid cited patents simply list the conventional additives useful in dentifrice compositions. There is no disclosure of the use of the betaine as the exclusive surfactant in the production of a high foaming dentifrice. There is also no disclosure nor recognition of the necessity to limit the humectant to polyethylene glycol and/or sorbitol, and the thickening agent to nonionic gums such as hydroxyethylcellulose, in order to obtain a cosmetically stable dentifrice in a betainequat system. There is also no disclosure of the use of a small amount of glycerin to chemically stabilize the fluoride content without adversely affecting the cosmetic stability of the quaternary-betaine system.
U.S. Pat. No. 4,363,795 and its counterpart International Patent Publication No. WO 80/00057 to Wahlstam disclose a cleaning agent for dentine surfaces containing a quaternary ammonium compound, an ampholytic tenside which may be an imidazoline or a betaine and a sequestering agent of the aminocarboxylic acid type which has a synergistic effect as to the antibacterial properties of the treating solution. All the examples are in the form of cleaning solution. There is no mention of dental creams, nor the use of humectants and thickening agents, nor the use of small amounts of glycerin to stabilize the fluoride content.
U.S. Pat. No. 4,130,637 discloses a specific group of betaine compound, or a mixture of said betaine and its corresponding carboxylic acid quaternary ammonium salt in a 9:1 ratio, as non-staining antimicrobial antiplaque agents in a dentifrice vehicle containing the aforelisted conventional humectants and gelling agents, and a nonionic surfactant. This patent fails to disclose the necessity of using a betaine surfactant exclusively, the specific nonionic gelling agent hydroxyethylcellulose, the specific humectant polyethylene glycol, and/or sorbitol, and a small amount of glycerin, at least 1% and up to a maximum of 10% and preferably 5% by weight, to chemically stabilize the fluoride-containing compound, in order to obtain a stable, high foaming quaternary-containing antiplaque dentifrice.
U.S. Pat. Nos. 4,117,107 and 4,117,108 also disclose a specific group of betaine compounds and their salts as antiplaque agents in a dentifrice vehicle containing the conventional humectants and gelling agents, as well as anionic/nonionic surfactants. There is no disclosure of an antibacterial quaternary ammonium compound, a fluoride, and a betaine surfactant exclusively. There is also no recognition of the specificity of humectant and gelling agent and the exclusion of anionic/nonionic surfactants in a quaternary-betaine system, which is necessary in order to obtain a stable high foaming antiplaque dentifrice, nor the need for a small amount of glycerin to chemically stabilize the fluoride-containing compound.
None of the above cited prior art discloses a cosmetically-stable antiplaque dentifrice with improved foaming and improved fluoride stability containing as the essential ingredients a cationic quaternary antiplaque compound, a zwitterionic betaine surfactant, a humectant compatible with the cationic antiplaque agent selected from the group consisting of polyethylene glycol and sorbitol, the nonionic gelling agent hydroxyethylcellulose, a fluoride-providing compound, and about 1-10% glycerin to stabilize said fluoride compound, in an aqueous vehicle containing a dental abrasive.